Method of treating photographic films



Patented Mar. 27, I934 PATENT OFFICE METHOD OF TREATING PHOTOGRAPHICFILMS Norman E. Titus, New York, N. Y.

No Drawing. Application July 9, 1932, Serial No. 621,745

4 Claims.

This invention is directed to a method of treating photographic filmsafter the same have been exposed, and has for one of its objects theprovision of a method for the removal of scratches and otherimperfections on the sensitized face of the film.

My invention while adapted for use in connection with all kinds ofphotography is particularly well adapted for the treatment of filmsemployed in newspaper work, for example, where enlargements are usuallymade from the original film, any scratches or other imperfections on thefilm being of course very pronounced and objectionable on enlargement.

More specifically the present invention provides a method for treatingfilms after exposure but before final processing whereby the desirableresults above mentioned are obtained.

Still more specifically the present invention provides a method for thetreatment of films in which after exposure the sensitized surface of thefilm is subjected to the action of heat, the degree of heat employedbeing just sufficient to effect a slight flowing or smoothing of thesensitive coating of the film to a point where the scratches or otherimperfections in this coating will disappear, or be so much reduced asto be negligible.

In the practice of my improved method the sensitive surface or emulsionof an exposed film after developing but before fixing is subjected tothe action of heat in a dark room, the heating being properly controlledso as to eliminate all possibility of damage to the film. This slightheating of the photographic emulsion causes a spreading or flowing ofthe same whereby any scratches or other imperfections on the surface ofthe emulsion will be filled in to such a extent as no longer to beobjectionable.

I appreciate that this application of heat to the emulsion isnecessarily a delicate operation and that the film must not be exposedto actinic rays in the process,so for these reasons I propose to subjectthe sensitized surface of the film to the action of infra-red rays, fromany suitable source but preferably generated electrically, to

permit me to avail myself of the nicety of control found in electricalapparatus.

The film to be treated can be kept in a dark room from which all lightis excluded, the infra red rays from a suitable source exterior to thedark room being directed to the surface of the photographic emulsion onthe film through a suitable barrier which will pass infra-red rays, butwill filter out all actinic rays. For example, a barrier of materialsuch as vulcanite may be substituted for the usual red dark room window,thus permitting the infra-red source to be located outside the dark roomwhere it is readily accessible, and permitting of the exclusion of allactinic rays from the film so that there is no danger whatsoever offogging of the film during the practice of my invention.

I do not wish to be limited to any particular device for the source ofthe infra-red waves but for the purpose of this application I maymention an ordinary copper bowl electric heater, a well known commercialarticle, as useful for the infra-red source.

In practice this heater may be placed in front of the above mentionedvulcanite barrier of the dark room and the film with its emulsion sidetoward the infra-red source passed behind the barrier. It will beappreciated of course that the input of this heater may be controlled toa nicety, and that by properly controlling the distance of the heatingdevice from the film, and the time of treatment, the desired results canbe obtained to perfection.

As above mentioned the heat is applied to the emulsion of the film inaccordance with the present invention after the film has been exposedand before fixing.

By the foregoing method it will be appreciated that all imperfectionssuch as striations, scratches, etc. on the emulsion of the film willeffectively be removed so that the enlargement from such film will befree of such imperfections. This is of great value in the newspaperindustry, for instance, where the pictures originally taken are usuallyenlarged before publication and where usually the pictures are takenunder conditions where the film is likely to be roughly handled be forebeing developed and fixed. My method is also useful in other fields ofphotography, as in the motion picture industry, for instance, where thepictures are taken on a small scale and are ver greatly enlarged onprojection.

What I claim is:-

1. The method of treating photographic films to eliminate scratches andother imperfections in the emulsion coating of the film which methodcomprises imposing non-actinic light rays upon the emulsion of apreviously exposed but unfixed film to heat the emulsion sufficiently toeffect a slight flowing of the emulsion whereby the scratches and otherimperfections therein will be smoothed out.

2. The method of treating photographic films to eliminate scratches andother imperfections in the emulsion coating of the film which methodcomprises exposing the film, developing and then before fixingsubjecting the emulsion of the film to the action of infra-red rays tothe exclusion of actinic rays to heat the emulsion sufficiently toeffect a flowing of the emulsion whereby the surface of the same will besmoothed out.

3. The method of treating photographic films to eliminate scratches andother imperfections from the emulsion surface of the same, which methodcomprises directing electrically generated light rays upon a mediumcapable of permitting of the passage of non-actinic rays whilepreventing the passage of actinic rays, and exposing the emulsion of anexposed but unfixed film to the light waves passed by said medium atsuch a distance from the source of the rays and for a surficient lengthof time to effect a slight heating of the emulsion sufficient to cause aslight flowing of the emulsion with a resultant smoothing of the surfaceof the emulsion.

4. The method of treating photographic films which comprises directingelectrically generated light rays upon a medium capable of permitting ofthe passage of non-actinic rays while preventing the passage of actinicrays, exposing the previously exposed, developed, but unfixed emulsionof a photographic film to the non-actinic rays passed by said mediumwhile controlling the time of exposure and the distance from the sourceof the non-actinic rays so that the emulsion is heated sufficiently tocause a slight flowing of the emulsion with a resultant smoothing out ofsaid face of the emulsion.

NORMAN E. TITUS.

